Electric safety plugs and sockets

ABSTRACT

An electrical connection device comprising at least two male and female plugs each constituted by a body of insulating material, the body of the male plug comprising a sleeve with a hollow core on the internal face of which are arranged at least two contacts mounted in slots on elastic means causing them to project from the internal face, while the body of the female plug comprises, at the front, an external tubular casing having an internal diameter equal, to within the necessary clearance, to the external diameter of the sleeve of the other plug, so as to permit the introduction of said sleeve into said tubular casing, and a cylindrical mandrel arranged axially inside the casing an having a diameter almost equal to the internal diameter of the sleeve of the other plug so as to fit into said sleeve, said mandrel being provided on its surface with at least two recesses intended to receive the projecting contacts of the other plug, and each containing a contact connected to one of the conductors terminating in said female plug.

United States Patent [191 Falbet [451 Oct. 16, 1973 1 ELECTRIC SAFETYPLUGS AND SOCKETS [76] Inventor: Jean Oswald Falbet, 18 rue Descartes,Agen, Lot-et-Garonne, France [22] Filed: June 21, 1971 [2]] Appl. No.:154,805

[30] Foreign Application Priority Data June 22, 1970 France 7022996 [52]US. Cl 339/14 R, 339/183, 339/211 [51] Int. Cl ..H01r 3/06, HOlr 17/18[58] Field of Search 339/14 R, 14 P, 182 R,

339/182 L, 182 T, 183, 211, 253 F, 253 L, 253 S, 254 R, 254 M, 255 R,255 A, 255 B, 255 L, 255 P, 259 R, 259 F, 213

Primary Examiner-Marvin A. Champion Assistant Examiner-Robert A. l-laferAttorneyWilfred G. Caldwell [5 7] ABSTRACT An electrical connectiondevice comprising at least two male and female plugs each constituted bya body of insulating material, the body of the male plug comprising asleeve with a hollow core on the internal face of which are arranged atleast two contacts mounted in slots on elastic means causing them-toproject from the internal face, while the body of the female plugcomprises, at the front, an external tubular casing having an internaldiameter equal, to within the necessary clearance, to the externaldiameter of the sleeve of the other plug, so as to permit theintroduction of said sleeve into said tubular casing, and a cylindricalmandrel arranged axially inside the casing an having a diameter almostequal to the internal diameter of the sleeve of the other plug so as tofit into said sleeve, said mandrel being provided on its surface with atleast two recesses intended to receive the projecting contacts of theother plug, and each containing a contact connected to one of theconductors terminating in said female plug.

2 Claims, 3 Drawing Figures PATENTEDUET 16 ms 3.766512 ELECTRIC SAFETYPLUGS AND SOCKETS The present invention relates to an electricconnection device between two electric lines each comprising at leasttwo conductors.

Conventional connection devices are usually composed of a male plugprovided with at least two projecting metal pins and a female plugcomprising two sockets with a hollow core, which are intended to receivethe pins of the male plug during the coupling; the connection is simplyeffected by engagement of the pins of the male plug in the sockets ofthe female plug.

These connection plugs, at present widely used, do not offer verysatisfactory conditions of safety for the user or for children who arealways tempted to handle them. In fact, when the two plugs are engaged,it frequently happens that the male plugs are not fully pushed home intothe corresponding sockets of the female plug, and that a portion ofthese latter remains visible. A person or a child handling plugs of thiskind can catch or touch this portion, thus risking a more or lessserious accident, depending on the nature of the current supplied tothe-plug. Furthermore, it is not infrequent for children to receiveelectric shocks by pushing into the sockets of female plugs undertension, elongated conducting objects such as knitting needles, pins,knife blades, etc.

In addition, it is clear that it is extremely dangerous to leave aconventional male plug under tension if it is not provided with aprotection device covering the projecting pins.

The present invention is intended to overcome thes drawbacks and toprovide an electrical connection device having great safety in use. Tothis end, this device is composed of at least two plug members, male andfemale, intended to be coupled together and each formed by a body ofinsulating material, at the rear of which terminate the electricalconductors. According to the invention, the body of the male plugcomprises at the front a sleeve with a hollow core, on the internal faceof which are arranged two contacts mounted in slots on elastic meanswhich cause them to project from this internal face, each contact beingconnected to one of the conductors which terminate at the said plug. Asregards the female plug, this is provided at the front, on the one handwith a tubular external casing having an internal diameter equal towithin the clearances, to the external diameter of the sleeve of theother plug so as to permit this latter to be introduced into thistubular casing, and on the other hand a cylindrical mandrel arrangedaxially inside the said casing and having a diameter equal, to withinthe clearances, to the internal diameter of the sleeve of the other plugso as to be capable of being housed in this latter. This mandrelcomprises on its surface two recesses intended during coupling toreceive the projecting contacts of the other plugs and each containing afixed contact connected to one of the conductors terminating at the saidfemale plug. With the exception of the contacts and of the conductorswhich terminate at the contacts, the male and female plugs are made ofinsulating material, for example of hard synthetic material.

The coupling together of the plugs according to the invention iseffected by placing the plugs end to end and bringing the sleeve of themale plug into engagement so as to be housed in the space of the femaleplug comprised between the mandrel and the tubular casing of the femaleplug. At the beginning of this introduction, each contact of the maleplug, mounted on elastic means, is pushed back into its slot by themandrel on the female plug. This contact then arrives at the level ofthe recess which is provided in the female plug and, by the effect ofelastic means, is introduced into this recess and comes up against thecontact of the female plug. In consequence, in this position, theelectrical connection is effected by means of these pairs of contactspressed one against the other.

The connection thus completed possesses remarkable consitions of safety.In fact, even if the male plug is not fully pushed into the female plug,no conductor under tension is visible and the user cannot in any case besubjected to an electric shock. Furthermore, no risk of electric shockis to be feared with respect to a female plug under tension; thecontacts of this plug are housed in the bottom of a recess and areinaccessible even by means of long objects which, if introduced into thefemale plug, will pass over the recess in which the contact of this plugis housed, without reaching it. In addition, a male plug under tensiondoes not constitute any particular danger since it does not comprise anyprojecting element capable, by accidental contact, either of causing ashort-circuit or of resulting in corporal accident.

The sleeve of the male plug is advantageously provided on its externalface with at least one rib intended to engage in a groove adapted andformed on the internal face of the casing of the female plug. This rib,engaged in the above-mentioned groove, will guide the introduction ofthis sleeve into the space of the female plug comprised between themandrel and the external casing. The introduction of the male plug intothe female plug can only be effected in a predetermined position, inwhich the rib of the male plug is arranged opposite the groove of thefemale plug; the contacts of each plug will be correspondingly locatedat the end of the introduction and will be placed naturally one on theother without trial and error.

In addition, the male plug may usefully be provided, at the level of therear extremity of its sleeve, with an external shoulder against whichthe front edge of the casing of the female plug comes into abutment.This position'of abutment defines the maximum position of engagement ofthe male plug .into the female plug, which position corresponds to theengagement of the contacts of both plugs.

According to a particular form of embodiment, thecontacts of the maleplug are each constituted by a metal nipple of substantiallyhemispherical shape, fixed to one extremity of a spring, and capable bypushing of being retracted by passage into its slot. Each of thesecontacts may also be formed by a metal ball imprisoned in its slot andcapable of projecting under the action of a spring.

The recesses of the female plug containing the contacts of this plug arepreferably provided on their front edge with an inclined slope intendedto facilitate the withdrawal of the contact of the male plug during thedisconnection of the male plug.

The male and female plugs according to the invention are provided with anumber of contacts suited to their utilization. They may each comprisetwo contacts which make them suitable for single-phase connections, forexample for domestic purposes. They may also comprise an additionalcontact acting as an earth contact and connected to an earthedconductor. In this latter case, the earth contact of the male plug mayuse fully be given smaller dimensions as compared with the othercontacts, while the corresponding recess of the female plug, of smallersize as compared with the other recesses, is given dimensions suitablefor this contact.

Thus, the phase contacts of larger size cannot become housed in thiscavity during the introduction of the male plug into the female plug,thus preventing any undesired electrical contact. The female plug may beformed integrally with a casing containing the safety fuses and intendedto be flush mounted in a wall. It will serve to distribute electricalenergy by simply engaging a male plug. The female plug may also be fixedto the extremity of an electric wire or cable for the purpose ofconnecting this wire or cable to another wire or cable provided on amale plug.

In addition, the external casing of the female plug is preferably fixedto the body of this plug by screwing on to a threaded portion of thisbody. Thus, it is possible for the user to separate this casing from theunit, which will facilitate the placing in position of this plug at theextremity of the electric wire to be equipped and will permit theconductors to be connected without difficulty to the correspondingcontacts.

Furthermore, the rear portions of the bodies of the female and maleplugs are additionally provided with grooves permitting them to begripped and easily handled.

Other characteristic features, objects and advantages of the inventionwill become apparent from the description which follows below withreference to the accompanying drawings, this description and drawingsbeing given only by way of non-limitative example.

In these drawings:

FIG. 1 shows exploded perspective views of a female plug according tothe invention, together with an oppositely arranged male plug;

FIG. 2 shows views in cross-section of a female plug and a male plugcoupled together;

FIG. 3 is a multi-purpose plug with four pins.

A female plug I intended to effect an electrical connection isessentially composed of a substantially cylindrical casing 2, a mandrel3 and a rear body 4 at which terminates the electric wire 5 comprisingelectric conductors such as 6. In the example shown, the wire 5comprises an earth conductor and two phase conductors.

The mandrel 3 and the body 4 are made by moulding and are formed in twoassembled halves fixed to each other by a screw 7. In addition, the body4 comprises a threaded portion 8 which is intended to receive a threadedportion 9 of the tubular casing 2.

In addition, the mandrel 3 comprises on its surface three recesses 10,11 and 12, in the bottoms of which are fixed metal blades connected tothe conductors 6. The blades of the recesses 10 and 11 are connected tothe phase conductors, while the blade of the recess 12 is connected tothe earth conductor of the wire 5.

In addition, the external casing 2 is provided on its internal face withtwo grooves, the function of which will become apparent later.

On the other hand, a male plug 13 is essentially constituted by a sleeve14 comprising two halves fixed to each other by means of screws such as15. These half sleeves may be manufactured by moulding a hard syntheticmaterial. The sleeve 14 is fixed by its rear portion to the body 16 ofthe plug, at which terminates an electric wire 17 containing electricconductors. At the junction of its two halves, the sleeve 14 is providedwith two ribs such as 18, projecting from its outer face. The sleeve 14is designed so as to be capable of being inserted, with a smallclearance, in the casing 2 of the female plug.

The shape of the hollow core of this sleeve 14 is similar to that of themandrel 3 of the female plug, so that this latter can be engaged andhoused with a small clearance in this core. Furthermore, the sleeve 14is provided on its internal face with three slots in which areimprisoned hollow metal balls 19,- 20 and 21, each mounted on a springsuch as 22 which urges them radially in the direction of the axis of thesleeve. These balls are connected through the intermediary of the springwhich acts on them, to the conductors of the wire 17 by means of lengthsof conducting wire such as 23, housed in grooves formed in the sleeve14. These channels may be located at the junction of the two halveswhich form the sleeve 14 and are constituted by grooves arranged on eachof these halves and coming opposite each other when the said halves areassembled together.

It can be seen from FIG. 2, representing in crosssection the plugscoupled together, that the mandrel 3 of the female plug has becomehoused inside the sleeve 14 of the male plug, which is in turnintroduced into the casing 2 of the said female plug. In this coupledposition, each ball 19, 20 or 21 comes opposite the corresponding recess10, 11 and 12 and, under the action of its spring, becomes appliedagainst the metal blade which lies on the bottom of each of the saidrecesses. Each conductor of the wire 5 is thus connected to a conductorof the wire 17.

It will furthermore be observed that the recess 12 corresponding to theearth conductor of the wire 5, and also the ball 21 corresponding to theearth conductor of the wire 17 are of small dimensions as compared withthe other recesses or balls. This arrangement prevents the ball 20, whenpassing over the recess 12 during coupling, from establishing contactwith the blade lying on the bottom of this recess 12. This ball has infact too large a diameter to be able to pass into the recess l2 and tomake contact with the blade of this recess. In addition, each recess 10,11 or 12 is provided at its front with a small inclined ramp whichenables the corresponding ball to be disengaged more easily at themoment of separation of the plug.

There will readily be appreciated the large degree of safety of use ofthe plugs such as described, in which no part under tension is visible.By this means all risks of electric shocks or short circuits are thuseliminated.

There has been shown in FIG. 3 a multi-connection plug falling withinthe scope of the present invention. The arms such as 24, 25, 26 and 27of this multiple plug have structures similar to those described. Thearms 24, 25 and 26 may for example be constituted by male plugs, whilethe arm 27 forms a female plug. Four plugs and sockets (one male andthree female) may be coupled to this multiple unit, one of them beingunder tension; the multiple unit thus serves to distribute electricalpower to the three others.

It will of course be understood that the present invention is notrestricted to the terms of the description above, but on the contrary itcomprises all the alternative forms within the scope of those skilled inthe art. The plugs according to the invention may also be built in; theymay also be shielded or serve as electric couplings for power lines.Similarly, the multiple units may be provided with a number of armsdifferent from that indicated by way of example.

When the plugs are not in use, they may be fitted with capswhich closetheir front portion. The cap intended for the female plug has the formof a disc with a projecting ring on one face, this ring being intendedto be housed, at the front of the female plug, between the casing 2 andthe mandrel 3. The cap of the male plug is constituted by a discprovided with a projecting nipple on one face, this nipple beingintended to be housed, at the front of the male plug, in the sleeve 14.Around this nipple, a projecting annular portion may be provided so asto cover the front extremity of the sleeve 14.

Furthermore, certain alternative forms of the invention may becontemplated. Thus, the male plug may constitute a night light; a smallbulb is mounted in the rear portion of the body and is electricallyconnected to the contacts. This rear portion, screwing on to the sleeve,is made of a translucent or transparent and coloured material.

I claim:

1. An electrical device for effecting connections between electric lineseach having at least two conductors, said device comprising at least onemale plug and one female socket mutually dimensioned to be coupledtogether; said plug and socket each comprising a body of insulatingmaterial through which the conductors extend; the body of the male plugcomprising a sleeve with a hollow core having an internal wall; at leasttwo contacts connected to the conductors extending into 6 said plug andcarried by said wall; the body of said female socket comprising anexternal tubular casing having an internal diameter substantially equalto the external diameter of the sleeve of the male plug to permit theintroduction of said sleeve into said tubular casing; said body of thefemale socket further comprising a cylindrical mandrel disposed axiallyinside said casing and having a diameter substantially equal to theinternal diameter of the sleeve of the male plug to fit in said sleeve;said wall of the sleeveof the male plug having slots; said contactscarried by the wall being retractively carried in the slots; elasticmeans in said slots and causing the contacts to project naturally fromsaid wall into said hollow core; the mandrel of said female sockethaving on its surface at least two recesses; contacts respectivelyconnected to the conductors and located within said recesses andcompletely within the outer surface of said mandrel whereby coupling ofsaid plug and socket causes the male contacts to'be biased intoengagement with the female contacts located inside said recesses.

2. A connection device as claimed in claim 1, in which said male plugand said female socket each comprise at least three contacts; onecontact of each of the plug and socket being an earth contact; saidearth contact of said male plug having smaller dimensions than the othercontacts of the male plug; and said mandrel touching the earth contactof said socket.

1. An electrical device for effecting connections between electric lineseach having at least two conductors, said device comprising at least onemale plug and one female socket mutually dimensioned to be coupledtogether; said plug and socket each comprising a body of insulatingmaterial through which the conductors extend; the body of the male plugcomprising a sleeve with a hollow core having an internal wall; at leasttwo contacts connected to the conductors extending into said plug andcarried by said wall; the body of said female socket comprising anexternal tubular casing having an internal diameter substantially equalto the external diameter of the sleeve of the male plug to permit theintroduction of said sleeve into said tubular casing; said body of thefemale socket further comprising a cylindrical mandrel disposed axiallyinside said casing and having a diameter substantially equal to theinternal diameter of the sleeve of the male plug to fit in said sleeve;said wall of the sleeve of the male plug having slots; said contactscarried by the wall being retractively carried in the slots; elasticmeans in said slots and causing the contacts to project naturally fromsaid wall into said hollow core; the mandrel of said female sockethaving on its surface at least two recesses; contacts respectivelyconnected to the conductors and located within said recesses andcompletely within the outer surface of said mandrel whereby coupling ofsaid plug and socket causes the male contacts to be biased intoengagement with the female contacts located inside said recesses.
 2. Aconnection device as claimed in claim 1, in which said male plug andsaid female socket each comprise at least three contacts; one contact ofeach of the plug and socket being an earth contact; said earth contactof said male plug having smaller dimensions than the other contacts ofthe male plug; and said mandrel of the female socket having a recess ofsmaller size than said other recesses for its earth contact whereby theother contacts of said male plug are precluded from touching the earthcontact of said socket.